Method of cold-drawing tapered filaments



y 1947- R. T. FIELDS METHOD OF COLD DRAWING TAPERED FILAMENTS 2 Sheets-Sheet 1 Filed April 29, 1945 IN V EN TOR.

Reuben Z'fields July 1, 1947. FlELDs 2,423,182

METHOD OF GOLD DRAWING TAPERED FILAMENTS Filed April 29, 1943 2 Sheets-Sheet 2 Reuben Z file/d5 INVENTOR.

respective spiral gears i8, i1 and I0, 2|.

. Figure 4 is an enlarged view in elevation: of the. drawing rolls showingthe line of ipath of the" filaments:

Figure 5 is a plan view of the drawing mils of- Flgure 4:

Flame 6 is an enlarged view, of the means shown in Figures 4 and 5, and

Figure 7 is a sectional view alongthe line 1-1 ofFigureB.

The drawing of the filament is accomplished by the difference in peripheral speeds between two pairs of drawing rolls. of which the pair ii and ii are the low speed rolls and the pair." and I4 are the high speed rolls. The rolls ii and I! are driven from a shaft 'll throughspiral gears iI and ll. The rolls l3 and II are similarly driven from the shaft ll by spiral gears 10 and III.

"The shaft II is driven by the shaft it through sprockets 2i and 22, and thus the relative speeds, of the two shafts are subject to control according to the'selection of the sprockets 2| and 22. The speeds of rotation of the pairs of rolls ii, I! and II, II are further variable by selection of Elie e peripheral speeds of rolls Ii and I! are the same, and the peripheral speeds of rolls l3 and 14 are the same. The ratio of the peripheral speed of the pair of rolls ll, it .to that of the pair of rolls li,. irgoverns the amount of stress imposed upon thefilament during'the operation of drawing. If, for example, the peripheral speed of the faster rolls is four times the peripheral speed of the slower rolls, then the draw ratio is, theoretically, 4:1, and the initial length of the filament is increased by 300 per cent during the drawing. Actually, however, because of the occurrence of some elastic recovery after the tension has been removed, the permanent stretch will usually be" somewhat less than 300 per cent, and the actual draw ratio somewhat less than 4:1, e. g., 3.7:1.

In actual construction, the pair of rolls i I, I2

may be placed, for convenience, directly above the pair i3, I 4. However, in order the better to diagram the course of the filament through the equipment, the rolls i3, H are shown mounted upon longer shafts than is actually the case, so that they project apparently into a position which is not directly beneath the other rolls, and correspondingly the alignment of parts 31, 24 and 25 in the horizontal is distorted in the figures.

As is clearly indicated in Figure 3, the axes of the rolls ii and I! are not parallel, the one tilting slightly 'below the horizontal and the other slightly above the horizontal. The actual angle between these positions should be of the order of about ten degrees, but is exaggerated in the figures for the sake of cleamess. The purpose of this tilting of the axes is to cause each of these rolls ii and ii to serve as a spreader for the other. Similarly, the axes of rolls i3 and it are not parallel to'each other, but the angle between these rolls needs to be only about one-half as great as that between'the rolls ii and ll, because the ribbon of drawn filaments which is handled by II, I is only approximately half as wide as the ribbon of undrawn filaments han- The filament 13 having tapered portions coming from a spool or directly from the preceding operation enters the system from the left in Figures l and 2 and is wrapped several times around the pair of rolls ii, 12, as indicated in Figures 2 and 3. The fact that these two .rolls are not parallel causes each one to serve to advance the positionof successive turns of the filament upon the other. After its last turn around these rolls, the filament 23 passes from the upper face of theroll ii to an idler roll 24 several feet distant,

; and thence back to the lower face of the roll i4,

spreading action is sufficient to space t e successive wraps.

and passes several times around the pair of rolls it. It" in the manner described in connection with rolls i I, |2 After its last turn around this pair of rolls i8, ll, the filament passes to a wind-up spool 25. v

The system is driven by a motor 2! by way of a countershaft 21. Through sprockets 28 and 10 this countershaft 2! drives the shaft II to operate. the two pairs of rolls H.- II and II, II. Through bevel gears II and a-countershaft' ii the countershaft 2'! drives a shaft 32 to operate the windup spool 28. The shaft 32 drives the spool 25 by way of a multiplate clutch 33, the slipping of which permits of the maintenance of a constant peripheral speed as the effective diameter of the spool 25 becomes increased by the filament wound upon it. It is desirable to provide a traverse mechanism by which the filament is guided to the spool 25 so as to form orderly layers thereupon, but this mechanism constitutes no part of the present invention and is omitted from the drawing for purposes of simplification.

The essential moving parts of the drawing equipment proper are the two pairs of rolls ii. I! and i3, i4.- The traction resulting from the several wraps of the filament around each of these pairs of rolls makes each pair serve as one of the points of application of the tension which results from the difference in peripheral speeds of the two pairs. These points of application of tension, or more briefly, "draw-points, are separated, in accordance with the invention, by a distance which is large compared with that of the prior art. This long span of filament between draw-points may be provided by installing the two pairs of rolls at a corresponding distance from each other, but the same result is accomplished by the arrangement already described, and illustrated in Figures '1 and 2, in which the span of filament between the two pairs of rolls is made as long as desirable by the interposition of a remotely placed idler, 24, while the rolls themselves are kept in actual proximity to each other for the sake of making the equipment more compact and the driving mechanism more simple.

The long span between draw-points is an im- Dortant feature of the invention and has numerous advantages. It reduces the risk of breakage of the filament which is undergoing elongation during its passage between draw-points, even though the magnitudes of the tension and the draw ratio are unchanged by the wide separation.

When the tapered filament is passed continuously between draw-points its portions of smallest diameter are generally the first to be elongated by the tension. They seem to be drawn immediately upon entering the span between the draw-points. Moreove the portions of largest diameter also become drawn to some extent.

The further drawing of the portions of largest diameter without tenslonal failure is accomplished as stated above by heating the filament between draw-points to a moderate temperature,

in accordance with the invention is particularly marked with polyamides suchas hexamethylene sebacamlde. The tension required to draw such a filament at about room temperature is' reduced by about 27% by changing the temperature from 27, O. to 82' C. while the tensile fully drawn. The large ends of the bristles are contained at least in part within the grip of the brush where a slight proportion of incompletely drawn filament is not a serious defect.

The foregoing details of drawing technique are applicable to a, single tapered filament or a group of tapered filaments. For commercial operations, it is preferable to simultaneously draw a plurality of filaments. This may be advantageously done by arranging a plurality of them in a ribbon-like group, i. e. parallel in the same plane and preferably each in contact with its neighbor during the entire operation. This can be accomplished through the use of guides. For instance a guide of rigid material (e. g. metal,

glass, plastic; ceramic, etc.) which presents a 8 a eurringunitsaredescribedinU.B.P.2MMI and. more particularly. in Alfthan and Holds enables a bundle of the drawn tapered filaments.

tobecutbyautomaticmeanslnasubsequentop- Ifthefilamentsaredeliveredtothe guidellandfirstdrawimrollinphasetheyob dinarily will continue in that manner throughout the drawing operation.

Theguide llmaytaheotherformsthantlie specific one shown. l 'or example. a roller 0! concave contour may be used. The roller or stationo guides may further be provided withgrooves correspondingtothe desired positionaot the several filaments. In fact, the prolonged usage .especially or a stationary uide will develop grooves as a result of abrasion by the filaments.

If th'e bundle of tapered filaments being fed to the drawing equipment is in. non-contact,. as is thegroup ll of threefilaments, shown lnl'igures 4 and 5, the desiredarranging oi. them into a rib- I not actually twisted around each other. The eon-v cavity of the face of the guide causes the several filaments to lie closely side by side. in actual contact at each recurrence of the maximum diameter of the filament.

The frictional resistance of the passage of the filaments over the guide, is reduced by having the filament approach the guide in wet condi-.

tion. This is readily achieved by having the filament pass through a container of water an route to the guide. Furthermore, the presence of a film of water upon the filaments is conducive to maintaining the several filaments of the ribbon-like group in contact with its neighbor.

The arrangement of the filaments side by side,

in phase, and in contact ofiers convenience in making an accurate measurement of the maximum diameter of the filament, for purposes of control, by measuring the total width of the ribbon and dividing by the number of filamen straight or slightly concave contour in.a plane at right angles to the filament, is interposed across the line of filaments coming from a previous operation or from storage spools, inv

show the unit structure of the filaments (which is somewhat exaggerated) -action of theguide and entry of the ribbon-like groups into the drawing equipment proper. only a few tapered units are shown in order to avoid confusion. In

actual practice the tapered units may be close together and have various contours. The tapers may be steep, gradual, curved or have relatively flat portions at the points of maximum or or minimum diameter. Suitable methods for preparing the undrawn tapered filaments with rewhich it contains.

But the principal p rp se and advantage of arranging the plurality of filaments in phase in a single plane before drawing is that it ensures exactly equal treatment of each individual filament in the drawing operation.- This is important in order to prevent the group from getting out of phase, and also because it eliminates frictional eifects between filaments in contact which, in the case of a random bundle of filaments subjected to drawing, are likely to cause weakening or breakage of one filament by the rubbing action of its neighbor. 1

Flgures'4 and 5 show also, on an enlarged scale, the passage of the filament 23 to, around and from the slow speed rolls ii and it of the drawing equipment already described. It will be observed that the spreader action of these two rolls causes the ribbon-like group of filaments 23 to progress from the rear to the front of this pair of rolls in its successive passages around them. It is to be noted also that the filament when once relieved of the tractive anchorage and,

' were:

subjected to tension in the beginning oflits pasof the drawing (a-b).

The invention provides a practicable, inexpensive. and effective method of cold-drawing, on a commercial scale, undrawn tapered filaments. In its preferred embodiment, involving, drawing -a plurality of filaments while side by side in a single plane, it subjects allvofthe individual filaments of a multiple groupto the same drawing treatment and thus maintains in phase axroup' of filaments delivered to the drawing equipmentin phase. "Moreover, it delivers the drawn filament stillin phase to subsequent operations, e. g., conditioning and cutting. r 7

The equipment required for the process of invention is simple. requires no close supervision, and can-be readily maintained in operating condition. The rolls between which the drawing tension is applied may be made of generous size and correspondingly sturdy. I Their faces may be made of metal or other durable. material, whereas the previously proposed machines have small rolls coated with rubber, or the like, which require frequent inspection and adjustment and need replacement or repair.

The recognition, in accordance with the invention, of the lack of need of completeness of drawing of the coarser portions of tapered filaments which are to serve as the butts of individual pieces used as "bristles" in paintbrushes, and the like, extends the utility of the invention to the cold-drawing of certain tapered filaments which by reason of their material and/or their dimensions can not, even by the process of the invention, be fully drawn in their coarser portions without breakage of their finer portions, and also provides a factor of safety'in the handling of tapered filaments which are not subject to this difficulty. 1

It will be evident that the'invention, with respect to the drawing technique itself, has its chief value in connection with the drawing of tapered filaments of which the unit length is short, e. g., filament to be used in paintbrushes but is also useful for tapered film. In the case of tapered filament of great unit length, such as is used as fishing leaders, the method of Smith, U. S. P. 2.292.905, which limits the distance between drawpoints. becomes commercially feasible. even without the use of rubber rolls to fix the draw-points. But the guide provided by the present invention as a means of maintaining a plurality of filaments in a ribbon-like group will be useful in connection with Smith's technique as applied to fishing leader filament.

, The invention will obviously applicable tov tapered filaments of materials other than those mentioned herein so far as they are similar thereto in significant properties.

The invention is not limited to the preparation of tapered filaments or bristles from the two specific polyamide filaments given above. On the contrary, it may be applied to any tapered filament which can be cold-drawn. The preferred polymeric filaments are polyamides of the types described in U. 8. Patents 2,071,250, 2,071,253, and 2,130,948. These polyamides are prepared from bifunc'tional polyamide-forming reactants and with hydrochloric acid thepolyamides yield poly-4 amide-forming reactants;j".p lamides of the :di-l. amine-dibasic acid type [yield a dia'mil'ie.hydio-v chloride and a dibaslc earboxylic,acidpwhereaa those of the amino acid type llleld an amino'acid hydrochloride. "As specific examples of such polyamides may b mentioned polydecamethylene adipamide, polyhexamethylene-sebacamide, poly pentamethylene sepacamidep polyoctamethylene adipamide,z6-aminocaproic acid polymenand 11- f aminou'nd'ecanoic acid polymer. Mixtures of the amide groups as amintegralpart of the main chain of atoms in the polymer. It is not essential that the linking group in the polymer chain consist solely of amide groups; they may also co ntain other groups, e. guester groups.

The polyamides are of two general types. those derived fromdiamines and suitable dicarboxylic acids or amide-forming derivatives of dibasic carboxylic acid, and those derivedfrompolymerizable amino acids oramide-forming'derivatives thereof, e. g. esters and lactams, On hydrolysis polyamides and interpolyamides may'also be used.

, Examples of such interpolyamides are those de- 'rived from hexamethylenedlamine, decamethyi-. enediamine, adipic acid and sebacic acid, .and

from hexamethylenediamide, adipic acid, and fi-aminocaproic acid. As examples of polyamides containing groupings other than amide-groupings may be mentioned ester-amide interpolymers, such as may be derived from a diamine. a dibasic acid, and a glycol or from an amino acid and an hydroxy' acid. For paint brushes preferred materials will include the superpolyamide hexamethylene sebacamide or hexamethylene adipamide alone or in admixture with 2% to 30%, and especially about 10%, of phenolformaldehyde resin. Such materials are described in assignee's application Serial No. 397,887.

The term polyamide" as used in this application includes polymers containing a plurality of groups of structure n o I II .N C

regardless'of the nature of the atom to which the indicated free linkages are attached. The term includes polymers derivedfrom a glycol and a diisocyanate or a diisothiocyanate.

The tapered filaments of this invention need not necessarily consist wholly of polyamide or modified polyamide. It is frequently desired to deluster and/ or color the filaments by adding a pigment to'the polymer or to the reactants from which the polymer is prepared. It is also useful in many cases to dye the filament, for example with nigrosine black, Sudan brown, etc. Thus, fishing lines or leaders may be made to resemble closely water of almost any color or turbidit by the proper choice of dyes or pigments. Bristles may also be made of any desired color and length. For paint brushes a unit length of 4 to 18 inches is practical.

It will be evident that the invention has its chief value in connection with the drawing of tapered filaments of which the unit length is short, e. g., a filament useful in paint brushes, and the like, but is also useful for longer tapered filaments, e. g., fishing leaders.

As many apparently widely difierent embodia 9 Iclaim:

l. The process which comprises subjectinga' cold-drawing organicpolymeric filament having recurring tapered units uniformly. disposed lengthwise, while passing between draw-points spaced at a distance at least five times the length or a tapered unit in drawn condition, to tension and heating the filament between such points to a temperature of approximately 40 C.-100'C.

2. The process which comprises subjecting a cold-drawing organic polymeric filament having recurring tapered units uniformly disposed lengthwise, while passing between draw-points spaced a distance at least five times the length oi a tapered unit in drawn condition to a tension insuilicient to cause tensional failure of the filament but sufiiclent to effect drawing of the portions of larger diameter to at least 80% of the extent to which they are capable of being drawn and heating the filament to a temperature from 50 and 90 C. between suchpoints.

3. The process which comprises subjecting a cold-drawing organic polymeric filament having recurring tapered units uniforml disposed lengthwise, while passing between draw-points paced a distance such that the travel of a fixed point of the filament requires at least two seconds and at least five times the length of a tapered unit in drawn condition, to a tension insufilcient to cause tensional failure of the filament but sufiicient to effect drawing of the portime of larger diameter to at least 80% of the extent to which they are capable of being drawn, and heating the filament between such points by contacting it with water at a. temperature between 50 and 90 C.

4. The process which comprises subjecting a illament'composed of a synthetic linear polyamide capable of being cold-drawn having recurring tapered units of short unit length uniformly disposed lengthwise, while passing between drawpoints spaced a distance such that the travel of a fixed point of the filament requires at least two seconds and at least five times the length of a tapered unit in drawn condition, to a tension insufilcient to cause tensional failure or the filament but sufilcient to eflect drawing of the portions of larger diameter to at least 80% of the extent to which they are capable of being drawn and heating the filament between such points-by contacting it with water at a temperature between 50 5. The process which comprises subjecting a cold-drawing polyhexamethylene sebaTcamide filament havin recurring er d units uniiormiy disposed lengthwise, while passing between drawpoints spaced 0. distance at least five times the lemth of a tapered unit in drawn condition, to a tension insufiicient to cause tensional failure of while passing between draw-points spaced a distance such that the travel of a fixed point of the filament requires at least two seconds and at least five times the length of a tapered unit in drawn condition, to a tension insuiiicient to cause tensional failure of the filament but sufilcient to eii'ect drawing of the portions or larger diameter to at least of the extent to which they are capable of being drawn and heating the filament between such points by contacting it with water at a temperature between 50 and C. for a period of at least one second. 7

. REUBEN T. FIELDS.

REFERENCES CITED The following references are oi record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,321,635 'Taylor June 15, 1943 2,142,912 Moncriefl et a1. July 3, 1939 2,217,707 Samerdyke et a1. Oct. 15, 1940 2,234,540 Fryer Mar. 11, 1941 2,292,905 Smith Aug. 11, 1942 1,878,692 Furness Sept. 20, 1932 936,243 Frappier Oct. 5, 1909 2,199,411 Lewis May 7, 1940 2,293,825 Hosfield. Aug, 25, 1942 2,137,235 Carothers Nov. 22, 1938 FOREIGN PATENTS Number Country Date 541,261 Great Britain Nov. 19, 1941 50,332 France Dec. 1, 1939 Addition to Patent No. 833,756

ll Certificate of Correction Patent No. 2,423,182. July 1, 1947. REUBEN T. FIELDS It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 37, for iself read itself; column 5, line 73, for or or read or; column 6, line 42, for an before route read en; column 8, line 74, for specified read 8 ecific; and that the said Letters Patent should be read with these corrections therem that the same may conform to the record of the case in the Patent Offioe.

Signed and sealed this 2nd day of September, A. D. 1947.

LESLIE FRAZER, I First Assistant Commissioner of Patents. 

